Merely giving the time and location may be enough to identify the police officers responsible. They normally have designated patrol areas, and if the incident occurred away from the boundaries of such an area (as there's some overlap) it should be clear who was driving.

How the hell is one supposed to provide that kind of info on a car that's driving away from you? "Gender"? "Race"? Is the sergeant expecting the offenders to turn around and stick their tongues out at you as they leave the scene?